The disclosure of Japanese Patent Application No. 2000-259298, filed Aug. 29, 2000, including the specification, drawings and abstract, is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates to a power output apparatus and a motor vehicle provided with the same, and more particularly to a power output apparatus capable of outputting power to a plurality of drive shafts, including a first drive shaft, a motor vehicle including a power output apparatus, and control methods thereof.
2. Description of Related Art
There has been proposed power output apparatus for a four-wheel drive vehicle having electric motors respectively attached to a front axle connected to a front wheel and a rear axle connected to a rear wheel and a power output apparatus for a four-wheel drive motor vehicle having electric motors respectively attached to rotating shafts of four wheels. In these power output apparatus, the electric motor is driven by using electric power charged in a battery or the electric motor is driven by using electric power obtained by operating a generator with power from an internal combustion engine.
Further, as other power output apparatuses, there have been proposed by the applicant a power output apparatus in which power is output to a first drive shaft by using power from an internal combustion engine and charged and discharged electric power of a battery by a planetary gear and two electric motors and power is output from a third electric motor to a second drive shaft by using the charged and discharged electric power of the battery (described in Japanese Patent Publication No. 9-175203, hereinafter, referred to as a mechanical distribution type power output apparatus), and a power output apparatus in which power is output to a first drive shaft by using power from an internal combustion engine and charged and discharged electric power of a battery by a twin-rotor electric motor having a first rotor connected to an output shaft of the internal combustion engine and a second rotor connected to a first drive shaft, and a second electric motor attached to the first drive shaft, and power is output from a third electric motor to a second drive shaft by using the charged and discharged electric power of the battery (described in Japanese Patent Publication No. 11-332020, hereinafter, referred to as an electrical distribution type power output apparatus).
In the case that the aforementioned power output apparatus is mounted to a moving body, particularly to a vehicle, it is necessary to output the power in correspondence to a motion requirement for the moving body. For example, in the case that the power output apparatus is mounted on the vehicle, both power for moving the vehicle forward and power for moving the vehicle backward are required.
In the apparatus that drives the electric motor by using the electric power charged in the aforementioned battery, and the apparatus that drives the electric motor by using the electric power generated with the power from the internal combustion engine, it is possible to switch an operation between forward movement and backward movement only by changing a direction of rotation of the electric motor, so that there is no problem in switching the direction. However, in the former, since it requires a long time to charge the battery, it is impossible to stand against a long time continuous use, and in the latter, since it is necessary to take into consideration an efficiency of power generation and an efficiency of the electric motor, energy efficiency is reduced.
In the electrical distribution type power output apparatus and the mechanical distribution type power output apparatus which have been proposed by the applicant, a part of the power from the internal combustion engine is directly output to the first drive shaft so as to rotate the first drive shaft. Further, it is normal to set the direction of rotation of the first drive shaft at this time to a direction of rotation according to a direction for moving the vehicle forward. Accordingly, in the case of moving the vehicle backward, that is, in the case of reverse rotation of the first drive shaft, it is necessary to take into consideration the power directly output from the internal combustion engine. In this case, in the electrical distribution type power output apparatus, an example of a control in the case of reverse rotation of the first drive shaft has been proposed in Japanese Patent Publication No. 11-332020, mentioned above.
It is one aspect of the invention to improve the practicability of a power output apparatus.
In accordance with a first aspect of the invention, there is provided a power output apparatus capable of outputting power to a plurality of drive shafts, including a first drive shaft. The power output apparatus is provided with an internal combustion engine having an output shaft, a power splitting and integrating mechanism, a first electric driving apparatus, a second electric driving apparatus, a third electric driving apparatus, a battery, a state of charge detecting apparatus, and a reverse rotation driving controller.
In this case, the power splitting and integrating mechanism is connected to rotating shafts comprising an output shaft in the internal combustion engine, the first drive shaft and a power splitting and integrating shaft, and is structured such that when power is input from any rotating shaft of the three rotating shafts, the power is split into the other two rotating shafts, and when the power is input from any two rotating shafts of the three rotating shafts, the input power is integrated so as to be output to the other rotating shaft. The first electric driving apparatus is connected to the power splitting and integrating shaft, and can generate electric power. The second electric driving apparatus is connected to the first drive shaft and can generate electric power. The third electric driving apparatus is connected to at least one drive shaft other than the first drive shaft and can generate electric power. The battery can send and receive electric power with respect to the first electric driving apparatus, the second electric driving apparatus and the third electric driving apparatus, respectively. The state of charge detecting apparatus detects a state of charge of the battery. The reverse rotation driving controller controls driving of the internal combustion engine, driving of the first electric driving apparatus, driving of the second electric driving apparatus and driving of the third electric driving apparatus on the basis of the detected state of charge so that power for reverse rotation opposite a normal rotation is output to the first drive shaft and the at least one drive shaft connected to the third electric driving apparatus at the suitable torque ratio.
In the power output apparatus of the first aspect of the invention, the driving of the internal combustion engine, the driving of the first electric driving apparatus, the driving of the second electric driving apparatus and the driving of the third electric driving apparatus are controlled by the reverse rotation driving controller on the basis of the state of charge of the battery. Accordingly, the power output apparatus can output the power for reverse rotation opposite the normal rotation to the first drive shaft and the at least one drive shaft connected to the third electric driving apparatus at the suitable torque ratio.
In accordance with a second aspect of the invention, there is provided a power output apparatus capable of outputting power to a plurality of drive shafts including a first drive shaft. The power output apparatus is provided with an internal combustion engine and integrating action of the power splitting and integrating mechanism. As a result, it is possible to increase an energy efficiency at a degree not having an effect of the splitting and integrating action of the power splitting and integrating mechanism, and it is possible to easily control the first electric driving apparatus that outputs the power to the first drive shaft.
In accordance with a third aspect of the invention, there is provided a motor vehicle including the power output apparatus of the first aspect or the second aspect of the invention. In this case, the first drive shaft is connected to a front axle connected to a front wheel of a vehicle. The at least one drive shaft connected to the third electric driving apparatus is connected to a rear axle connected to a rear wheel of the vehicle. The normal rotation corresponds to a rotation for moving the vehicle forward.
In accordance with the third aspect of the invention, there is provided a motor vehicle capable of outputting power to a front wheel and a rear wheel.
The motor vehicle is provided with a front-wheel-power output apparatus, a rear-wheel-power output apparatus, a battery, a state of charge detecting apparatus, and a backward movement driving controller.
In this case, the front-wheel-power output apparatus has a first electric motor capable of outputting power to the front wheel. The rear-wheel-power output apparatus has a second electric motor capable of outputting power to the rear wheel. The battery supplies an electric power to the front-wheel-power output apparatus and the rear-wheel-power output apparatus. The state of charge detecting apparatus detects a state of charge of the battery. The backward movement driving controller sets a torque ratio between the front wheel and the rear wheel on the basis of the detected state of charge. The backward movement driving controller also controls driving of the front-wheel-power output apparatus and driving of the rear-wheel-power output apparatus so that the power for moving the vehicle backward at the set torque ratio is output to the front wheel and the rear wheel.
In the motor vehicle of the third aspect of the invention, since the torque ratio between the front wheel and the rear wheel is set on the basis of the state of charge of the battery, and the driving of the front-wheel-power output apparatus and the driving of the rear-wheel-power output apparatus are controlled so that the power for moving the vehicle backward at the suitable torque ratio is output to the front wheel and the rear wheel, it is possible to control the backward movement in correspondence to the state of charge of the battery.